1. Technical Field
This invention relates to a method of forming a connector press-connecting terminal, and more particularly to a method of forming a press-connecting terminal (press-connecting blades) provided in a press-connecting connector, to which a conductor of a cable is electrically press-connected.
2. Related Art
Typical examples of known conventional connector press-connecting terminals of the type described are shown in FIGS. 5 and 6, respectively. In the press-connecting terminal 50 shown in FIG. 5, a pair of press-connecting blades 52a and 52b are disposed in opposed relation to each other, and a plating treatment is applied to contact surfaces (encircled by a broken line in this Figure) of these blades in order to enhance the reliability of the connection to a cable. In this case, there are also the type of products to which the plating treatment is not applied.
In the press-connecting terminal 60 shown in FIG. 6, upstanding opposite (right and left) side wall plates, formed by pressing a metal sheet, are inwardly bent at their respective intermediate portions by press working to provide a pair of opposed press-connecting blades 62a and 62b, respectively. In this case, also, a plating treatment is usually applied to the surface of the metal sheet.
3. Problems to be Solved
In the former terminal shown in FIG. 5, in accordance with the required performance, the plating need to be applied to the contact surfaces of the two press-connecting blades 52a and 52b for contact with a conductor of the cable. In this case, after the press-shaping operation, the plating treatment is applied (that is, the intermediate- or the post-plating is needed), and therefore the cost increases.
On the other hand, in the latter terminal shown in FIG. 6, the plating is beforehand applied to the metal sheet, and therefore the cost is reduced. However, in the press working, the metal sheet is pressed merely once (one shot) or a plurality of times in a die, and therefore a distal end portion of each of the press-connecting blades 62a and 62b is thinned as shown in FIG. 7, or is susceptible to cracking, and besides there has been encountered a problem that the plated surfaces of these portions are much roughened.
It is an object of this invention to provide a method of forming a connector press-connecting terminal by press-shaping a metal sheet, beforehand plated with an electrically-conductive material, in which each press-connecting blade is not reduced in thickness at its distal end, but has a uniform thickness, and the surface of the press-connecting blade is finished into a good condition free from cracking, plated-surface roughening and so on. With this method, the invention seeks to stabilize the quality of the product (i.e., the connector press-connecting terminal member), to secure a properly press-connected condition of a cable, and to enhance the yield rate of the products.
[Means for Solving the Problems]
According to the present invention, there is provided a method of forming a connector press-connecting terminal including a pair of opposed press-connecting blades formed respectively on opposite right and left side wall plates thereof formed by a metal sheet, the press-connecting blades being adapted to be electrically press-connected to a connection end portion of a cable in a gripping manner; CHARACTERIZED in that the method comprises the steps of:
forming cuts respectively in press-connecting blade-forming portions of the flat metal sheet beforehand plated with an electrically-conductive material;
applying a plurality of drawing operations to the press-connecting blade-forming portion at each of the cut portions sequentially from a proximal end portion of the press-connecting blade to a distal end portion thereof, thereby forming the press-connecting blade of a bent shape; and
press-bending the metal sheet along two longitudinal lines, passing respectively through the cut portions, so that the opposite right and left sidewall plates, having the opposed press-connecting blades, respectively, are formed upright respectively at opposite side edges of a bottom wall plate of the terminal.
In this case, the cuts are not particularly limited to any special configuration, and may have merely a slit-like configuration, or may be in the form of a stamped-out triangular hole corresponding to the bent shape of the press-connecting blade. In the case of using the stamped-out triangular hole, any protrusion is not formed on the bottom wall plate when the press-connecting blade of the bent shape is formed, and this is pleasing in appearance.
Preferably, the press-connecting blade-forming step comprises the drawing of the proximal end portion of the press-connecting blade to be formed into the bent shape, the drawing of an intermediate portion of the press-connecting blade, and the drawing of the distal end portion of the press-connecting blade, and these drawing operations are carried out such that a curvature of the distal end portion of the press-connecting blade is gradually reduced.
In the drawing of the press-connecting blade by press-shaping, the drawing of the proximal end portion of the press-connecting blade, disposed near to the cut portion, is first effected, and subsequently the intermediate portion of the bent press-connecting blade is effected, and finally the drawing of the distal end portion of the press-connecting blade is effected. Thus, the plastically-deformed portions of the metal sheet are sequentially shifted from the proximal end portion of the press-connecting blade to the distal end portion thereof, and therefore the abrupt plastic deformation of the press-connecting blade portion is avoided, and besides the press-connecting blade of a uniform thickness is formed. However, the drawing does not need to be effected in a three-stage process, but the press-connecting blade may be finished in a two-stage process, or a four- or more stage drawing process can be used, depending on the amount (degree) of projection of the press-connecting blade.
Preferably, the metal sheet is cut obliquely to a plane thereof so that the press-connecting blade can have such a contour that an apex end surface of the press-connecting blade, formed on each of the opposite right and left side wall plates, becomes a slanting surface slanting inwardly downwardly relative to the bottom wall plate of the terminal. Therefore, in the operation for press-connecting the cable, the cable can be smoothly inserted between the opposed press-connecting blades, and can be positively and firmly press-connected to the two press-connecting blades in a fitted manner.
The connector press-connecting terminal member, produced by this production method, can be used as a terminal for press-connection to various cables including a coaxial cable and a parallel paired cable.